1 /* mountpoint management 2 * 3 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/init.h> 15 #include <linux/fs.h> 16 #include <linux/pagemap.h> 17 #include <linux/mount.h> 18 #include <linux/namei.h> 19 #include <linux/gfp.h> 20 #include "internal.h" 21 22 23 static struct dentry *afs_mntpt_lookup(struct inode *dir, 24 struct dentry *dentry, 25 unsigned int flags); 26 static int afs_mntpt_open(struct inode *inode, struct file *file); 27 static void afs_mntpt_expiry_timed_out(struct work_struct *work); 28 29 const struct file_operations afs_mntpt_file_operations = { 30 .open = afs_mntpt_open, 31 .llseek = noop_llseek, 32 }; 33 34 const struct inode_operations afs_mntpt_inode_operations = { 35 .lookup = afs_mntpt_lookup, 36 .readlink = page_readlink, 37 .getattr = afs_getattr, 38 }; 39 40 const struct inode_operations afs_autocell_inode_operations = { 41 .getattr = afs_getattr, 42 }; 43 44 static LIST_HEAD(afs_vfsmounts); 45 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); 46 47 static unsigned long afs_mntpt_expiry_timeout = 10 * 60; 48 49 /* 50 * check a symbolic link to see whether it actually encodes a mountpoint 51 * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately 52 */ 53 int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key) 54 { 55 struct page *page; 56 size_t size; 57 char *buf; 58 int ret; 59 60 _enter("{%x:%u,%u}", 61 vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique); 62 63 /* read the contents of the symlink into the pagecache */ 64 page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0, 65 afs_page_filler, key); 66 if (IS_ERR(page)) { 67 ret = PTR_ERR(page); 68 goto out; 69 } 70 71 ret = -EIO; 72 if (PageError(page)) 73 goto out_free; 74 75 buf = kmap(page); 76 77 /* examine the symlink's contents */ 78 size = vnode->status.size; 79 _debug("symlink to %*.*s", (int) size, (int) size, buf); 80 81 if (size > 2 && 82 (buf[0] == '%' || buf[0] == '#') && 83 buf[size - 1] == '.' 84 ) { 85 _debug("symlink is a mountpoint"); 86 spin_lock(&vnode->lock); 87 set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags); 88 vnode->vfs_inode.i_flags |= S_AUTOMOUNT; 89 spin_unlock(&vnode->lock); 90 } 91 92 ret = 0; 93 94 kunmap(page); 95 out_free: 96 page_cache_release(page); 97 out: 98 _leave(" = %d", ret); 99 return ret; 100 } 101 102 /* 103 * no valid lookup procedure on this sort of dir 104 */ 105 static struct dentry *afs_mntpt_lookup(struct inode *dir, 106 struct dentry *dentry, 107 unsigned int flags) 108 { 109 _enter("%p,%p{%pd2}", dir, dentry, dentry); 110 return ERR_PTR(-EREMOTE); 111 } 112 113 /* 114 * no valid open procedure on this sort of dir 115 */ 116 static int afs_mntpt_open(struct inode *inode, struct file *file) 117 { 118 _enter("%p,%p{%pD2}", inode, file, file); 119 return -EREMOTE; 120 } 121 122 /* 123 * create a vfsmount to be automounted 124 */ 125 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) 126 { 127 struct afs_super_info *super; 128 struct vfsmount *mnt; 129 struct afs_vnode *vnode; 130 struct page *page; 131 char *devname, *options; 132 bool rwpath = false; 133 int ret; 134 135 _enter("{%pd}", mntpt); 136 137 BUG_ON(!d_inode(mntpt)); 138 139 ret = -ENOMEM; 140 devname = (char *) get_zeroed_page(GFP_KERNEL); 141 if (!devname) 142 goto error_no_devname; 143 144 options = (char *) get_zeroed_page(GFP_KERNEL); 145 if (!options) 146 goto error_no_options; 147 148 vnode = AFS_FS_I(d_inode(mntpt)); 149 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) { 150 /* if the directory is a pseudo directory, use the d_name */ 151 static const char afs_root_cell[] = ":root.cell."; 152 unsigned size = mntpt->d_name.len; 153 154 ret = -ENOENT; 155 if (size < 2 || size > AFS_MAXCELLNAME) 156 goto error_no_page; 157 158 if (mntpt->d_name.name[0] == '.') { 159 devname[0] = '#'; 160 memcpy(devname + 1, mntpt->d_name.name, size - 1); 161 memcpy(devname + size, afs_root_cell, 162 sizeof(afs_root_cell)); 163 rwpath = true; 164 } else { 165 devname[0] = '%'; 166 memcpy(devname + 1, mntpt->d_name.name, size); 167 memcpy(devname + size + 1, afs_root_cell, 168 sizeof(afs_root_cell)); 169 } 170 } else { 171 /* read the contents of the AFS special symlink */ 172 loff_t size = i_size_read(d_inode(mntpt)); 173 char *buf; 174 175 ret = -EINVAL; 176 if (size > PAGE_SIZE - 1) 177 goto error_no_page; 178 179 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL); 180 if (IS_ERR(page)) { 181 ret = PTR_ERR(page); 182 goto error_no_page; 183 } 184 185 ret = -EIO; 186 if (PageError(page)) 187 goto error; 188 189 buf = kmap_atomic(page); 190 memcpy(devname, buf, size); 191 kunmap_atomic(buf); 192 page_cache_release(page); 193 page = NULL; 194 } 195 196 /* work out what options we want */ 197 super = AFS_FS_S(mntpt->d_sb); 198 memcpy(options, "cell=", 5); 199 strcpy(options + 5, super->volume->cell->name); 200 if (super->volume->type == AFSVL_RWVOL || rwpath) 201 strcat(options, ",rwpath"); 202 203 /* try and do the mount */ 204 _debug("--- attempting mount %s -o %s ---", devname, options); 205 mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options); 206 _debug("--- mount result %p ---", mnt); 207 208 free_page((unsigned long) devname); 209 free_page((unsigned long) options); 210 _leave(" = %p", mnt); 211 return mnt; 212 213 error: 214 page_cache_release(page); 215 error_no_page: 216 free_page((unsigned long) options); 217 error_no_options: 218 free_page((unsigned long) devname); 219 error_no_devname: 220 _leave(" = %d", ret); 221 return ERR_PTR(ret); 222 } 223 224 /* 225 * handle an automount point 226 */ 227 struct vfsmount *afs_d_automount(struct path *path) 228 { 229 struct vfsmount *newmnt; 230 231 _enter("{%pd}", path->dentry); 232 233 newmnt = afs_mntpt_do_automount(path->dentry); 234 if (IS_ERR(newmnt)) 235 return newmnt; 236 237 mntget(newmnt); /* prevent immediate expiration */ 238 mnt_set_expiry(newmnt, &afs_vfsmounts); 239 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 240 afs_mntpt_expiry_timeout * HZ); 241 _leave(" = %p", newmnt); 242 return newmnt; 243 } 244 245 /* 246 * handle mountpoint expiry timer going off 247 */ 248 static void afs_mntpt_expiry_timed_out(struct work_struct *work) 249 { 250 _enter(""); 251 252 if (!list_empty(&afs_vfsmounts)) { 253 mark_mounts_for_expiry(&afs_vfsmounts); 254 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 255 afs_mntpt_expiry_timeout * HZ); 256 } 257 258 _leave(""); 259 } 260 261 /* 262 * kill the AFS mountpoint timer if it's still running 263 */ 264 void afs_mntpt_kill_timer(void) 265 { 266 _enter(""); 267 268 ASSERT(list_empty(&afs_vfsmounts)); 269 cancel_delayed_work_sync(&afs_mntpt_expiry_timer); 270 } 271